Emergency power supplies for light sources adapted to transform a lighting apparatus into an emergency lighting apparatus are known. Two main cases thereof can be identified.
The emergency inverter type, constituted by a device integrating or not integrating a safety source interposed between the power supply grid and the network power supply, so to be able to power supply it from safety source and ensure the operation thereof even in the absence of the power supply grid.
The second case, related to the present description, is known as a Converter Kit and is generally associated with ordinary power supplies that are however independent therefrom, i.e. capable of turning on and supplying the light source by means of an incorporated power supply thereof capable of coordinating the operation thereof with that of the network power supply by means of a suitably designed interface section. When there is no the network voltage, the converter kit supplies the light source by drawing energy from the rechargeable battery (safety source).
For example, the public document US 2014/0312699 illustrates a backup power supply with constant power for apparatuses of LED type which comprises a battery that is loaded while an AC alternating current source is activated. A switch-provided circuit switches between the AC power supply and the emergency supply by moving contacts onto different positions. When there is no AC source, a group of capacitors charged by the battery supplies current to the primary of a flyback converter that operates in discontinuous manner. The secondary of the flyback converter supplies constant power to the LED.
The public document EP 2 011 211 illustrates an emergency lighting device for providing illumination to a light source such as a LED. The device comprises a battery and a recharge circuit supplied with the network voltage and provided with a flyback converter. The flyback converter is configured for recharging the battery. The device also comprises a control circuit supplied during emergency operation by the battery and in capable of managing the power supply of the LED.